7. Electron Transfer Reactions and Redox Catalysis on Gold Nanofilms at Soft Interfaces

The dispute about the exact and correct mechanism of the electron transfer (ET) reactions at liquid–liquid interfaces has lasted for decades. The ET reaction at ITIES was studied experimentally and by computer simulations for a model system. This model system contains \( {\text{Fc}}^{ + } / {\text{Fc}}^{0} \) as an organic soluble electron donor and \( {\text{Fe}}({\text{CN}})_{6}^{3 - /4 - } \) as a water-soluble electron acceptor. The current results indicate that the ET reaction takes place by a potential independent homogeneous reaction in the aqueous phase, while the observed potential dependence stems from that of the concomitant ion transfer reaction of ferrocenium. Functionalization of the interface with metallic nanoparticles significantly improves kinetics of the interfacial reaction by changing reaction mechanism to a bipolar pathway, when NP is acting as an electrically conducting bipolar electrode between the two phases. Therefore, we highlight the catalytic property of a metal nanoparticle film toward heterogeneous electron transfer reactions and explain this property from the point of view of the Fermi level equilibration theory.